Spinal stabilization systems and methods of use

ABSTRACT

An orthopedic device is adapted to fixate the spinous processes of vertebral bones. The device includes at least one bone engagement member. When implanted, a bone engagement member is located on each side of a spinous process and adapted to forcibly abut the side of each spinous process.

REFERENCE TO PRIORITY DOCUMENTS

This application is a divisional of and claims priority to co-pending U.S. patent application Ser. No. 14/065,291 of the same title filed on Oct. 28, 2013, which is a divisional of and claims priority to U.S. patent application Ser. No. 12/011,772 of the same title, filed on Jan. 29, 2008 and issued as U.S. Pat. No. 8,568,453 on Oct. 29, 2013, and which claims priority of co-pending U.S. Provisional Patent Application Ser. No. 60/898,010 filed Jan. 29, 2007, and U.S. Provisional Patent Application Ser. No. 60/921,570 filed Apr. 3, 2007, each which is incorporated herein by reference in its entirety. Priority of the aforementioned filing dates is hereby claimed and the disclosures of the Provisional Patent Applications are hereby incorporated by reference in their entirety.

BACKGROUND

The present disclosure relates to devices and methods that permit fixation and stabilization of the bony elements of the skeleton. The devices permit adjustment and maintenance of the spatial relationship(s) between neighboring bones. Depending on the specifics of the embodiment design, the motion between adjacent skeletal segments may be limited or completely eliminated.

Spinal degeneration is an unavoidable consequence of aging and the disability produced by the aging spine has emerged as a major health problem in the industrialized world. Alterations in the anatomical alignment and physiologic motion that normally exists between adjacent spinal vertebrae can cause significant pain, deformity, weakness, and catastrophic neurological dysfunction.

Surgical decompression of the neural tissues and immobilization of the vertebral bones is a common option for the treatment of spinal disease. Currently, vertebral fixation is most frequently accomplished by anchoring bone screws into the pedicle portion of each vertebral body and then connecting the various screw fasteners with an interconnecting rod. Subsequent rigid immobilization of the screw/rod construct produces rigid fixation of the attached bones.

The growing experience with spinal fusion has shed light on the long-term consequences of vertebral immobilization. It is now accepted that fusion of a specific spinal level will increase the load on, and the rate of degeneration of, the spinal segments immediately above and below the fused level. As the number of spinal fusion operations have increased, so have the number of patients who require extension of their fusion to the adjacent, degenerating levels. The rigidity of the spinal fixation method has been shown to correlate with the rate of the degenerative progression of the adjacent segments. In specific, implantation of stiffer instrumentation, such as rod/screw implants, produced a more rapid progression of the degeneration disease at the adjacent segment than use of a less stiff fixation implant.

An additional shortcoming of the traditional rod/screw implant is the large surgical dissection required to provide adequate exposure for instrumentation placement. The size of the dissection site produces unintended damage to the muscle layers and otherwise healthy tissues that surround the diseased spine. A less invasive spinal fixation implant would advantageously minimize the damage produced by the surgical exposure of the spine.

SUMMARY

The preceding discussion illustrates a continued need in the art for the development of a minimally invasive method of vertebral fixation of reduced rigidity.

In a first embodiment, there is disclosed an orthopedic device adapted to fixate the spinous processes of vertebral bones. The implant includes at least one bone engagement member located on each side of a spinous process and adapted to forcibly abut the side of each spinous process. The engagement member only abuts a single spinous process and does not abut another surface of a second spinous process. The implant further includes a connector member adapted to interconnect the bone engagement members on each side of a spinous processes. The connector member is defined by a long axis that is substantially longitudinal and parallel to the spinous processes. The implant further includes a connection between the bone engagement members and the connector member. The connection is capable of reversibly transitioning between a first state, wherein the orientation between the engagement member and the connector member is changeable in at least one plane and a second state, wherein the orientation between the engagement member and the connector member is rigidly affixed. The implant further includes a cross member extending across the vertebral midline and adapted to adjustably couple the longitudinal connector members that are located on each side of the vertebral midline. The cross member reversibly transitions between a first state, wherein the orientation between the longitudinal connector members and the cross member is changeable and a second state, wherein the orientation between the longitudinal connector members and the cross member is rigidly affixed.

In a second embodiment, there is disclosed an orthopedic device adapted to fixate the spinous processes of vertebral bones. The orthopedic device includes at least one bone engagement member located on each side of at least two adjacent spinous processes and adapted to forcibly abut the side of the spinous processes. The engagement member is substantially comprised of a contoured rod and contains at least one side aperture that permits contact between bone graft material and the spinous processes. The device further includes a cross member extending across the vertebral midline and adapted to adjustably couple the longitudinal bone engagement members that are located on each side of the vertebral mid line. The cross member is capable of reversibly transitioning between a first state, wherein, the orientation between the longitudinal bone engagement members and the cross member is changeable in at least one plane and a second state, wherein the orientation between the longitudinal bone engagement members and the cross member is rigidly affixed.

In another embodiment, there is disclosed an orthopedic device adapted to fixate the spinous processes of vertebral bones. The device includes at least one bone engagement member located on each side of at least two adjacent spinous processes and adapted to forcibly abut the side of the spinous processes. The bone engagement member is substantially comprised of a plate that contains a curvilinear end surface adapted to engage a connecting member, wherein the curvilinear end surface is not located on a bone engaging surface of the plate. The device further includes a cross member extending across the vertebral midline and adapted to adjustably couple the longitudinal bone engagement members that are located on each side of the vertebral mid line. The cross member has a complimentary surface adapted to engage the curvilinear end surfaces of the longitudinal bone engagement members and to provide a changeable attitude between them. The cross member is further adapted to reversibly transition between a first state, wherein the orientation between the longitudinal bone engagement members and the cross member is changeable in at least one plane and a second state, wherein the orientation between the longitudinal bone engagement members and the cross member is rigidly affixed.

In another embodiment, there is disclosed an orthopedic device adapted to fixate the spinous processes of the vertebral bones wherein the device is adapted to accepted an additional bone fastener that is placed into the base of the spinous process in a substantially horizontal trajectory.

In yet another aspect, an orthopedic implant is disclosed. In one embodiment, the implant comprises (i) a first bone abutment surface movably joined to a first segment of a first connecting member; (ii) a second bone abutment surface movably joined to a first segment of a second connecting member, the first bone abutment surface being aligned to substantially face the second bone abutment surface; and (iii) a locking member positioned between each of the first and the second bone abutment surfaces and comprising a first side wall, a second side wall, at least one connecting wall configured to extend between the first and second walls, and an internal cavity at least partially bound by the walls. A second segment of the first connecting member enters the internal cavity of the locking member through an aperture of the first side wall, and a second segment of the second connecting member enters the internal cavity of the locking member through an aperture of the second side wall. An actuator member is positioned to enter the internal cavity through an aperture of the connecting wall, and is configured to, upon advancement in a first direction, concurrently cause advancement of each of the first and the second bone abutment surfaces towards the locking member positioned therebetween.

In another embodiment, the implant comprises: (i) a first bone abutment surface movably joined to a first segment of a first interconnecting member at a first coupling; (ii) a second bone abutment surface movably joined to a first segment of a second interconnecting member at a second coupling, the first bone abutment surface being aligned to substantially face the second bone abutment surface; and (iii) a locking member movably joined to each of first and second interconnecting members and being positioned an equal distance from each of the first coupling and the second coupling. The locking member comprises an actuator that is configured to: upon advancement in a first direction, cause concurrent advancement of each of the first and the second bone abutment surfaces towards one another; and upon advancement in a second direction, cause concurrent movement of each of the first and the second bone abutment surfaces away from one another.

In another aspect, a method for stabilization of a spinal segment compromising a superior vertebral bone and an immediately adjacent inferior vertebral bone is disclosed. In one embodiment, the method comprises: (i) approaching a posterior aspect of the spinal segment; (ii) identifying an inter-spinous space, the inter-spinous space being positioned between a spinous process of the superior vertebral bone and a spinous process of the inferior vertebral bone; (iii) positioning a central body of an orthopedic implant at least partially within the inter-spinous segment; (iv) positioning a first bone abutment surface of the orthopedic implant on a left side of the spinous process of the superior vertebral bone and the spinous process of the inferior vertebral bone; (v) positioning a second bone abutment surface of the orthopedic implant on a right side of the spinous processes of the superior vertebral bone and the spinous process of the inferior vertebral bone; (vi) actuating an advancement feature of the central body to produce a concurrent movement of the first bone abutment member and the second bone abutment member towards the inter-spinous space; and (vii) capturing each of the spinous processes of the superior and of the inferior vertebral bones between the first and second bone abutment surfaces. The first bone abutment surface is movably joined to a first segment of a first connecting member, the second bone abutment surface is movably joined to a first segment of a second connecting member and the first bone abutment surface is aligned to substantially face the second bone abutment surface. The advancement feature of the central body is further configured to cause a concurrent movement of each of the first and second bone abutment surfaces towards one another from a first to a second position and to retain them in the second position.

Other features and advantages will be apparent from the following description of various embodiments, which illustrate, by way of example, the principles of the disclosed devices and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows perspective views of an exemplary embodiment of an orthopedic implant.

FIG. 2A shows an exploded view of the implant embodiment.

FIG. 2B illustrate multiple views of a locking member of the implant.

FIG. 3A shows a section of a locking mechanism of the implant in the locked and rigid position.

FIG. 3B shows a section of a locking mechanism of the implant in the un-locked and non-rigid position.

FIG. 4 shows a section of another locking mechanism of the implant.

FIG. 5A and FIG. 5B show a perspective view of the embodiment prior to screw placement and after screw placement, respectively.

FIG. 6 shows a second embodiment of the implant attached to a vertebral bone model.

FIG. 7A shows a side perspective of the embodiment of FIG. 6.

FIG. 7B shows a cross-sectional view of the device of FIG. 7A.

FIG. 8 shows an alternative locking mechanism of the implant.

FIG. 9 shows a member of the alternative locking mechanism.

FIG. 10 illustrates a cross-sectional view of the alternative locking mechanism.

FIG. 11 illustrates a perspective view of another embodiment of an orthopedic implant.

FIG. 12 shows the device of FIG. 11 in multiple orthogonal planes.

FIG. 13A shows an exploded view of the implant.

FIG. 13B illustrates a cross-sectional view of the locking mechanism.

FIG. 14 shows a perspective view of another embodiment of an orthopedic implant.

FIG. 15 shows an exploded view of the implant in FIG. 14.

FIG. 16 shows a cross-section view of the locking mechanism of the implant embodiment of FIG. 14.

FIG. 17 shows a modular attachment device.

FIG. 18 illustrates an exploded view of the modular attachment device of FIG. 17.

FIGS. 19A and 19B show a locking mechanism between the modular attachment device of FIG. 17 and the device of FIG. 14. The locking mechanism is shown in the unlocked state in FIG. 19A and in the locked state in FIG. 19B.

FIG. 20 shows a perspective view of another embodiment attached to vertebral bones.

FIG. 21 illustrates the device of FIG. 20 in an exploded view.

FIG. 22 shows a cross-sectional view through the locking mechanism of the device.

DETAILED DESCRIPTION

FIG. 1 shows a perspective view of an exemplary embodiment of a vertebral fixation implant. The implant can be anchored across multiple levels of vertebral bones via one or more spiked anchor members, such as members 105. For clarity of illustration, the device is shown attached to two adjacent vertebral bones. The vertebrae are represented schematically and those skilled in the art will appreciate that actual vertebral bones may include anatomical details that differ from those shown in FIG. 1. An exploded view of the implant is shown in FIG. 2A.

In a device intended to immobilize two vertebral bones, four anchor members 105 are interconnected by “H” shaped rod connector 109. The rod connector 109 includes a pair of rods that extend generally parallel to the vertebral midline and a single cross rod that crosses the vertebral midline. The cross rod interacts with a locking element that can be used to adjust the position of the cross rod relative to the pair of rods that extend generally parallel to the vertebral midline.

The rod connector interacts with a plurality of anchor members 105 that are positioned so that each can be affixed onto each side surface of a spinous process of each vertebra. The anchor member 105 is adapted to affix onto the side surface of the spinous process and can have various structures suited for such a purpose. In the illustrated embodiment, the anchor member contains an inner abutment surface 1052 that contains structures adapted to attach to the spinous process, such as spiked projections 1053. Each anchor member 105 also has an outer surface 1055 that contains a receptacle member 1056 adapted to receive a segment of rod connector 109. A locking member 110 (FIG. 28) is adapted to interact with receptacle member 1056 and rigidly affix rod connector 109 onto an anchor member 105. As described below, the locking member 110 is sized and shaped to be positioned inside a central cavity of receptacle member and locked in place therein, Each anchor member 105 can optionally contain a bore hole 1058 that is adapted to accept a bone screw or other fastener that, when applied, can increase the fixation strength of the device onto bone.

Through its interaction with locking member 110, receptacle member 1056 of anchor member 105 is adapted to allow adjustable placement of rod connector 109 relative to member 105 and provide an adjustable orient for spike members 1053 relative to the spinous process. In Use, the anchor members 105 are attached to the spinous processes by driving the spike members 1053 into the spinous processes. After each of two members 105 are forcibly driven into opposing sides of a spinous process of a single spinal vertebra, locking member 110 is compressed into the central cavity of receptacle member 1056. The locking member 110 interacts with the receptacle member 1056 and the rod connector 109 such that a segment of rod connector 109 is rigidly affixed within the receptacle member 1056. The locking member 110 is adapted to reversibly transition from a first un-locked state in which member 1056, member 110 and the interacting segment of rod connector 109 are movable to a second locked state wherein the device members are rigidly affixed to another, as described more fully below.

FIG. 2B shows various views of an exemplary embodiment of locking member 110. In the illustrated embodiment, locking member 110 has a spherical inner cavity 1102 adapted to accept a spherical end segment 1092 of connecting rod 109. Outer surface 1104 of locking member 110 is adapted to fit within and interact with a conical inner surface of receptacle member 1056 of anchor member 105. An outer wall relief 1109 is adapted to accept a retention pin. A second relief, 1106, is located on an open end of locking member 110 and allows the formation of deformable flap with protrusion tip 1108.

A cross-sectional view of the locking mechanism is shown in FIG. 3A (locked state) and in FIG. 3B (unlocked state). In the unlocked state shown in FIG. 3B, spherical end segment 1092 of connecting rod 109 is non-rigidly retained within cavity 1102 of member 110, permitting movement of connecting rod 109 relative to member 110 in one or more planes. With the application of a compressive load by a locking device (not shown), member 110 is forcibly advanced into the conical inner surface of receptacle member 1056. The advancement of locking member 110 into receptacle 1056 produces a centripetal force that rigidly immobilizes the connecting rod 109 to anchor member 105. The interaction of protrusion tip 1108 of locking member 110 with a relief on the inner wall of receptacle member 1056 (FIG. 3A) will maintain the construct in the locked position even after the locking instrument is removed.

While the inner cavity 1102 of member 110 can accept a spherical end segment 1092 of connecting rod 109, the flat surrounding segment 1103 of the inner aspect of member 110 can alternatively accommodate and interact with a cylindrical segment of rod 109. With member 110 in the unlocked position and a cylindrical segment of rod 109 engaged, member 110 can translate along the cylindrical segment of rod 109 and produce a device of variable length. In this configuration, rotational movement between segment 105 and interconnecting rod 109 occurs at the interface between member 11 O and receptacle 1056 as well as within the second locking mechanism shown in FIG. 4.

A second locking mechanism can be used to maintain the device in a locked configuration. The second locking mechanism can be located within the rod connector 109 and actuated by the advancement of threaded screws 1094 into a complimentary threaded bore hole on connecting rod 109, as shown in FIG. 4. For clarity of illustration, the threads are not shown in FIG. 4. This second locking mechanism exerts a compressive load onto locking member 110 and maintains the device in the locked configuration. It also places a compressive load across each of the two anchor members 105 placed on opposing sides of a spinous process and keeps the spiked projections 1053 rigidly affixed to bone.

Bone fixation may be strengthened further by the placement of bone screws or similar fasteners through bore holes within the anchor members 105, such as bore hole 1058. The insertion of bone screws into the anchor members 105 is illustrated in FIGS. 5A and 5B. Bores 1058 are positioned in member 105 so as to provide a substantially axial (i.e., horizontal) screw trajectory and advance the distal screw segment into the base of the spinous process. Preferably, each of the two opposite screws anchored onto a single spinous process are adapted to follow a non-parallel trajectory so as to further enhance bone fixation. In addition, the screw top may be angled so as to provide a Morse-taper like fit within the bore hole 1058. Alternatively, a secondary feature may be added to lock the bone screw onto anchor member 105 after the screws are fully seated into the underlying bone. An additional tab 1057 may be used to connect two anchor members 105 across the mid line of the spinous process. This variation is shown in FIG. 6, which shows the tab 1057 that extends over the spinous process. In an embodiment, the tab 1057 has malleable sides that permit relative motion between each anchor member 105. The tab 1057 may also contain a central bore that is adapted to accept a bone fastener anchored into the spinous process. FIG. 7 A show a lateral view of the device of FIG. 6, while FIG. 7B illustrates a lateral cross sectional view that shows the bone screw extending along the long axis of the spinous process through the tab 1057.

An alternative locking member that reversibly locks connecting rod 109 and receptacle 1056 of member 105 is shown in FIGS. 8 through 10. This embodiment has a modified version of the locking member, which is shown in FIG. 9. Locking member 122 has an inner cavity 1222 that is sized and shaped to accept spherical end 1092 of connecting rod 109. Member 122 has conical outer wall 1224 that fits within receptacle member 1056. Relief 1225 of wall 1224 is adapted to accept a retention pin. Another relief, 1227, is located on the inferior surface of locking member 122 and allows the formation of deformable flap with protrusion tip 1228. A key hole relief 1229 allows the superior aspect of member 122 to angle inward in response to a compressive load and constrict inner cavity 1222 of the locking member 122.

A cross-sectional view of the alternate embodiment of the locking mechanism is shown in FIG. 10 in the locked configuration. With the application of a compressive load by a locking device (not shown), member 122 is forcibly advanced into the conical inner surface of receptacle member 1056. Because of the difference in wall angle between the outer wall of member 122 and the inner wall of receptacle 1056, advancement of member 122 into receptacle 1056 produces a centripetal inclination of the walls of member 122 and rigidly immobilizes the connecting rod 109 to anchor member 105. The interaction of protrusion tip 1228 of locking member 122 with a relief on the inner wall of receptacle member 1056 will maintain the construct in the locked position even after the locking instrument is removed. As previously discussed with reference to member 110, a cylindrical segment of connector rod 109 may be alternatively used to interact with member 122 and produce a device of variable length.

The device may be also used to fixate more than two vertebral levels. In this procedure, the total length from the top-most to lower-most spinous process is measured and the number of spinous processes to be affixed is counted. An interconnecting longitudinal rod of the appropriate length is selected and coupled with the appropriate number of bone anchor members 105. Either one, both or none of the longitudinal interconnecting rod ends may be spherical. Members 110 of the anchor member 105 will couple and interaction with cylindrical portion of the longitudinal rod to provide an adjustable spacing between members 105. An interconnecting rod with the appropriate number of member 105 is placed on each side of the mid line.

Starting at a selected level, a locking compression device (not shown) is used to drive the spikes of the members 105 into each side of the spinous process. The locking compression device is left in position and the procedure is repeated onto the next spinous process level. Prior to the rigid fixation of member 110 within receptacle 1056, the attitude of member 105 may be adjusted by rotation and translation relative to the interconnecting rod. After anchoring the opposing member 105 into the spinous process, the locking device is left in place and the procedure is sequentially moved to another level. After fixation of a number of levels has been accomplished, the surgeon can place a cross member across the mid line and couple each of the longitudinal rods. This step can be performed after some or all members 105 have been rigidly affixed to their designated vertebral level. After cross member placement, the locking compression device attached to each secured level is removed. If desired, an additional bone screw fastener may be placed through bore hole 1058.

FIGS. 11 through 13 illustrate an additional device embodiment. A perspective view is shown in FIG. 11 while multiple orthogonal views are illustrated in FIG. 12. The device 1705 is comprised of two bone engaging members 1710 that are each formed of a pair of contoured or curved rods that extend outwardly from a central member 1717. The bone engaging members 1710 are separated by a space that is sized and shaped to receive a bone structure, such as the spinous process of a vertebral body. Opposed surfaces of the bone engaging members 1710 have attachment means such as spikes, knurls or other protrusions on the bone-facing aspect of each bone-engaging member. An interconnecting member 1720 comprised of an elongated rod is adapted to extend through a fitted bore hole within each central member 1717. A locking screw 1725 is adapted to reversibly lock a segment of interconnecting member 1720 within each central member 1717.

FIG. 13A shows an exploded view of the device. FIG. 138 illustrates a cross-sectional view through the locking mechanism. Central member 1717 has a central bore 1728 along and the long access that is adapted to accept locking screw 1725 and a second bore 1730 that is adapted to accept interconnecting ember 1720. Compressible spherical member 1732 has bore hole 1734 and open side notch 1735. As shown in FIG. 138, member 1732 is contained within bore hole 1728 of central member 1717 and surrounds a segment of interconnecting member 1720 in the assembled device. Locking screw 1725 abuts a surface of compressible spherical member 1732. In the unlocked state, interconnecting member 1720 is freely movable within member 1732. Spherical member 1732 can also rotate within central hole 1728, thereby proving an adjustable relationship between each bone engaging members 1710 and interconnecting rod 1720. With advancement of locking screw 1725, spherical member 1732 is forcibly compressed onto rod 1720 and immobilized within central hole 1728, thereby locking interconnecting rod 1720 within bone engaging member 1710.

In placement of the device onto bone, each bone engaging member 1710 is situated on an opposite side of the spinous processes to be immobilized. A compressive force is applied by a locking instrument (not shown) across members 1710 so as to drive the spikes into the side of the spinous processes of neighboring vertebrae and immobilize them. The interconnecting member 1720 is used to maintain compression even after the locking instrument has been removed. In this regard, the threaded locking screws 1725 are advanced to provide a locked engagement between interconnecting member 1720 and each member 1710. After implantation, multiple apertures 1723 exist in this rod-based device that advantageously permit access to the underlying bone of the spinous processes. Bone graft material can be placed through apertures 1723 and into contact with the spinous processes in order to form and augment the bone fusion mass.

FIGS. 14 through 16 illustrate an additional device embodiment. A perspective view is shown in FIG. 14 while an exploded view in shown in FIG. 15. The device 208 is comprised of two bone engaging members 210 and 212 that are opposed to one another. The bone engaging members 210 and 212 are separated by a space that is sized and shaped to receive a bone structure, such as the spinous process of a vertebral body. Opposed surfaces of the bone engaging members 210 and 212 have attachment means such as spikes, knurls or other protrusions on the bone-facing aspect of each bone-engaging member. In application, each member is situated on an opposite side of the spinous processes to be immobilized. A compressive force is applied by a locking instrument (not shown) across members 210 and 212 so as to drive the spikes into the side of the spinous processes of neighboring vertebrae and immobilize them. A slotted interconnecting plate 218 is used to maintain compression even after the locking instrument has been removed.

A cross-sectional view of the implant's locking mechanism is shown in the locked position in FIG. 16. A spherical member 222 has threaded central bore 2224 and accepts threaded screw 226 (threads not shown for either member). Member 222 resides within bores 230 (FIG. 15) of plate members 210 and 212. Bore 230 is adapted to permit insertion of member 222 from the bottom. A securement member, such as a protrusion within bore 230, prevents member 222 from emerging from the top. Retention pins 234 retain member 222 within bore 230 and prevent its rotation relative to long axis of bore 230. The top surface of each member 210 and 212 contains a spherical protrusion 240 that has the same center of rotation as seated member 222. The inferior surface of interconnecting plate 218 has a complimentary spherical indentation that compliments the spherical surface protrusion 240 of members 210 and 212. In this way, each member 210 and 212 can be independently oriented relative to interconnecting plate 218. With advancement of threaded screw 226 into member 222, the interconnecting plate 218 is locked relative to members 210 and 212.

A modular device 1402 is shown in FIGS. 17 through 19. The modular device is adapted to reversibly lock onto an implanted device 208 and thereby extend the affixing of an adjacent vertebral body to the implanted device 208. FIG. 17 shows the modular device attached to an implanted device 208. FIG. 18 shows the modular device in an exploded state adjacent to an assembled device 208, which is substantially identical or similar to the device shown in FIGS. 14-16. A locking mechanism 1405 is adapted to reversibly lock onto the device 208 by interacting with a hole 1407 in the device 208. The locking mechanism 1405 includes a pin 1410 that fits into an expandable head 1415 that is positionable within the hole 1407.

FIG. 19A shows the locking mechanism 1405 in a unlocked state with the device 208. The pin 141 O is partially positioned within the expandable head 1415, which is located inside bore 1407 of the bone engaging member 210. Member 210 has a curved inner surface that is adapted to interact with the complimentary outer surface of head 1415 and permit movement therebetween. With the pin 1410 in the unlocked position shown in FIG. 19A, modular device 1402 and member 21 O are movable relative to one another in one or more planes. FIG. 19B shows the locking mechanism 1405 in a locked state such that the pin 1410 has been fully inserted into the expandable head 1415. This has caused the head 1415 to expand outward within bore hole 1407 and provide an interfering, locked engagement between the modular device and the bone engaging member 210. The two devices are thus locked relative to one another.

FIGS. 20 through 22 illustrate an additional device embodiment. FIG. 20 shows the device attached to vertebral bones and FIG. 21 shows the device in an exploded state. The device is comprised of two bone engaging members 2005 formed of elongated rods configures to be positioned adjacent the vertebral bodies. The bone engaging members 2005 are separated by a space that is sized and shaped to receive a bone structure, such as the spinous process of a vertebral body. Opposed surfaces of the bone engaging members 2005 have attachment means such as spikes, knurls or other protrusions on the bone-facing aspect of each bone-engaging member.

With reference to FIG. 20-22, the bone engaging members 2005 are connected to a central member 2015 by a pair of curved connecting arms 2025 with enlarged heads 2030. The connecting arms 2025 and the bone engaging members 2005 are joined together by retention pins 2050. The heads 2030 can pivot inside the cavity of central member 2015 such that the bone engaging members 2005 can move toward and away from the spinous processes.

A threaded locking screw 2035 engages threaded locking nut 2040 within the central cavity of central member 201˜. Edges 2042 of member 2040 are contained within indentions 2032 of heads 2030. As locking screw 2035 is rotated and locking nut is moved towards the head 2037 of screw 2035, heads 2030 of connecting arms 2025 are rotated within the central cavity of member 2015. Rotation of heads 2030 cause the bone engaging members 2005 to pivot inward by virtue of the curved shape of the connecting arms 2025. The bone engaging members 2005 thereby are caused to exert a compressive force onto the spinous processes and to be secured thereto. Conversely, rotation of the locking 2035 in the reverse direction will cause the bone engaging member 2005 to move away from the spinous processes.

The disclosed devices or any of their components can be made of any biologically adaptable or compatible materials. Materials considered acceptable for biological implantation are well known and include, but are not limited to. stainless steel, titanium, tantalum, shape memory alloys, combination metallic alloys, various plastics, resins, ceramics, biologically absorbable materials and the like. Any components may be also coated/made with osteo-conductive (such as deminerized bone matrix, hydroxyapatite, and the like) and/or osteo-inductive (such as Transforming Growth Factor “TGF-8,” Platelet-Derived Growth Factor “PDGF,” Bone-Morphogenic Protein “BMP,” and the like) bio-active materials that promote bone formation. Further, any surface may be made with a porous ingrowth surface (such as titanium wire mesh, plasma-sprayed titanium, tantalum, porous CoCr, and the like), provided with a bioactive coating, made using tantalum, and/or helical rosette carbon nanotubes (or other carbon nanotube-based coating) in order to promote bone in-growth or establish a mineralized connection between the bone and the implant, and reduce the likelihood of implant loosening. Lastly, the system or any of its components can also be entirely or partially made of a shape memory material or other deformable material.

Although embodiments of various methods and devices are described herein in detail with reference to certain versions, it should be appreciated that other versions, embodiments, methods of use, and combinations thereof are also possible. Therefore the spirit and scope of the appended claims should not be strictly limited to the description of the embodiments contained herein. 

The invention claimed is:
 1. An orthopedic implant, comprising: a first bone abutment surface movably joined at a coupling to a first segment of a first connecting member; a second bone abutment surface movably joined to a first segnent of a second connecting member, said first bone abutment surface being aligned to face said second bone abutment surface; and a locking member positioned between each of said first and said second bone abutment surfaces and comprising a first side wall, a second side wall, at least one connecting wall configured to extend therebetween, and an internal cavity at least partially bound by said walls; wherein a second segment of said first connecting member enters said internal cavity through an aperture of said first side wall, a second segment of said second connecting member enters said internal cavity through an aperture of said second side wall; wherein an actuator member enters said internal cavity through an aperture of said connecting wall; and wherein said actuator member extends from a first end to a second end along a central axis and, upon advancement in a first direction, concurrently causes advancement of each of said first and said second bone abutment surfaces towards said locking member positioned therebetween; and wherein said first and second bone abutment surfaces are each divided into a first and a second bone abutment segment by a plane that includes said central axis of said actuator member.
 2. The implant of claim 1, wherein said first connecting member is coupled to said first bone abutment member at said first segment of said first connecting member and coupled to said locking member at said second segment of said first connecting member.
 3. The implant of claim 2, wherein said movably joining of said first connecting member and said first bone abutment member permits rotational movement between them.
 4. The implant of claim 1, wherein said second connecting member is coupled to said second bone abutment member at said first segment of said second connecting member and coupled to said locking member at said second segment of said second connecting member.
 5. The implant of claim 4, wherein said movably joining of said second connecting member and said second bone abutment member permits rotational movement between them.
 6. The implant of claim 1, wherein at least one of said first and second bone abutment surfaces comprises a feature configured to increase fixation onto bone.
 7. The implant of claim 1, wherein advancement of said actuator in said first direction concurrently causes advancement of each of said first and said second bone abutment surfaces towards one another.
 8. The implant of claim 1, wherein advancement of said actuator in a second direction concurrently causes retraction of each of said first and said second bone abutment surfaces away from said locking member positioned therebetween.
 9. The implant of claim 1, wherein advancement of said actuator in a second direction concurrently causes retraction of each of said first and said second bone abutment surfaces away from one another.
 10. The implant of claim 1, wherein said actuator comprises a screw.
 11. The implant of claim 1, wherein said implant is at least partially manufactured from at least one of: a metallic material or a plastic material.
 12. An orthopedic implant, comprising: a first bone abutment surface movably joined to a first segment of a first interconnecting member at a first coupling; a second bone abutment surface movably joined to a first segment of a second interconnecting member at a second coupling, said first bone abutment surface being aligned to face said second bone abutment surface; and a locking assembly movably joined to each of said first and second interconnecting members and being positioned an equal distance from each of said first coupling and said second coupling, said locking assembly having a first side wall, a second side wall, at least one connecting wall configured to extend therebetween, and an internal cavity at least partially bound by said walls; wherein said internal cavity is entered by: a) a second segment of said first interconnecting member through an aperture of said first side wall; b) a second segment of said second interconnecting member through an aperture of said second side wall and c) an actuator member through an aperture of said connecting wall; wherein said actuator member extends from a first end to a second end along a central axis and comprises a segment seated within a receiving member that is at least partially positioned within said internal cavity; and wherein translation of said receiving member relative to said actuator member along said central causes concurrent advancement of each of said first and said second bone abutment surfaces towards one another.
 13. The implant of claim 12, wherein said coupling between said first interconnecting member and said first bone abutment member permits rotational movement between said first interconnecting member and said first bone abutment member.
 14. The implant of claim 12, wherein at least one of said first and second bone abutment surfaces comprises a feature configured to increase fixation onto bone.
 15. The implant of claim 12, wherein said translation of said receiving member relative to said actuator member causes concurrent advancement of each of said first and said second bone abutment surfaces towards one another.
 16. The implant of claim 15, wherein translation said member of said locking feature in a second direction causes concurrent retraction of each of said first and said second bone abutment surfaces away from one another.
 17. The implant of claim 12, wherein said actuator member comprises a screw.
 18. The implant of claim 12, wherein said implant is at least partially manufactured from at least one of: a metallic material or a plastic material.
 19. A method for stabilization of a spinal segment comprising a superior vertebral bone and an immediately adjacent inferior vertebral bone, said method comprising: approaching a posterior aspect of said spinal segment; identifying an inter-spinous space, said inter-spinous space being positioned between a spinous process of said superior vertebral bone and a spinous process of said inferior vertebral bone; positioning a central body of an orthopedic implant at least partially within said inter-spinous space; positioning a first bone abutment surface of said orthopedic implant on a left side of each of said spinous process of said superior vertebral bone and of said spinous process of said inferior vertebral bone; positioning a second bone abutment surface of said orthopedic implant on a right side of each of said spinous processes of said superior vertebral bone and of said spinous process of said inferior vertebral bone; and positioning a first segment and a second segment of said first bone abutment surface to abut each of said left side surface of said spinous process of said superior vertebral bone and said left side surface of said spinous process of said inferior vertebral bone, respectively; wherein said first bone abutment surface comprises a monolithic structure that is movably joined to a first segment of a first connecting member, said second bone abutment surface is movably joined to a first segment of a second connecting member and said first bone abutment surface is aligned to face said second bone abutment surface; wherein an advancement feature of said central body is configured to contact said first and second connecting members to cause a concurrent movement of each of said first and second bone abutment surfaces towards said central body.
 20. The method of claim 19, further comprising actuating said advancement feature by rotating an actuator member of said advancement feature in a first direction.
 21. The method of claim 20, wherein rotation of said actuator member in a second direction opposite said first direction causes concurrent movement of each of said first and second bone abutment surfaces away from one another.
 22. The method of claim 19, further comprising capturing each of said spinous process of said superior and inferior vertebral bones between said first and second bone abutment surfaces, said capturing being enhanced via a bone engagement feature on at least one of first and second bone abutment surfaces. 